Как правильно malloc для структуры и определенных переменных?

Я пытаюсь malloc для Racer, но я продолжаю получать ошибки в Valgrind, может кто-нибудь помочь мне понять, почему это не так, как у меня?Как правильно malloc для структуры и определенных переменных?

Valgrind сообщает мне, что ошибки в строках 49, 50 и 57 ... Я отметил их стрелками.

Вот мой racer.c код:

#define _BSD_SOURCE 
#include <stdlib.h> 
#include <stdio.h> 
#include <string.h> 
#include <time.h> 
#include <assert.h> 
#include <pthread.h> 
#include <unistd.h> 

long waitTime = DEFAULT_WAIT; 
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; 

// Does the setup work for all racers at the start of the program. 
void initRacers(long milliseconds){ 
    clear(); 
    if (milliseconds != 0){ 
     waitTime = milliseconds; 
    } 
    pthread_mutex_init(&lock, NULL); 
    srand(time(NULL)); 
} 

// Creates a new racer. 
Racer *makeRacer(char *name, int position){ 
    int remain; 
    int sizeOfRear = 0; 
    char *frontSide = "o>"; 
    char *rearSide = "~0="; 
    char *middleOfCar; 

    int lengthOfName = strlen(name); 
    int lengthOfRearSide = strlen(rearSide); 
    size_t sizeOfRacer = sizeof(Racer); 
-> Racer *nRacer = (Racer *)malloc(sizeOfRacer); 
-> nRacer->graphic = (char *)malloc(lengthOfName); 

    strncpy(nRacer->graphic, rearSide, lengthOfRearSide + 1); 
    strcat(nRacer->graphic, name); 
    sizeOfRear = strlen(nRacer->graphic); 

    remain = MAX_CAR_LEN - sizeOfRear; 
-> middleOfCar = (char *)malloc(remain); 
    for (int x = 0; x < remain - 2; x++){ 
     middleOfCar[x] = '-'; 
    } 
    strcat(middleOfCar, frontSide); 
    strcat(nRacer->graphic, middleOfCar); 
    nRacer->dist = 0; 
    nRacer->row = position; 
    return nRacer; 
}

и вот структура:

/// Rcr struct represents a racer position and display graphic. 
/// 
typedef struct Rcr { 

    /// current distance from starting line of the rear of the car 
    /// 
    int dist; 

    /// vertical position of the racer, i.e. "racing lane" 
    /// 
    int row; 

    /// graphic: the drawable text 
    /// 
    char *graphic; 

} Racer;

, valgrind Ошибки:

[email protected]:~/Desktop/Threads$ valgrind --leak-check=full --show-leak-kinds=all --track-origins=yes ./pt-cruisers one two 
==18972== Memcheck, a memory error detector 
==18972== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al. 
==18972== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info 
==18972== Command: ./pt-cruisers one two 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C31644: __strncpy_sse2_unaligned (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x401208: makeRacer (racer.c:52) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420093 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid read of size 1 
==18972== at 0x4C30C14: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40121F: makeRacer (racer.c:53) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420093 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C30C30: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40121F: makeRacer (racer.c:53) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420093 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C30C3F: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40121F: makeRacer (racer.c:53) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420096 is 3 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid read of size 1 
==18972== at 0x4C30F74: strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40122F: makeRacer (racer.c:54) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420093 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Conditional jump or move depends on uninitialised value(s) 
==18972== at 0x4C30C17: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x401289: makeRacer (racer.c:61) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Uninitialised value was created by a heap allocation 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40124A: makeRacer (racer.c:57) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C30C3F: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x401289: makeRacer (racer.c:61) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x54200e6 is 0 bytes after a block of size 6 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40124A: makeRacer (racer.c:57) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid read of size 1 
==18972== at 0x4C30C14: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4012A0: makeRacer (racer.c:62) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420093 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C30C30: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4012A0: makeRacer (racer.c:62) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x5420096 is 3 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid read of size 1 
==18972== at 0x4C30C33: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4012A0: makeRacer (racer.c:62) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x54200e6 is 0 bytes after a block of size 6 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40124A: makeRacer (racer.c:57) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== Invalid write of size 1 
==18972== at 0x4C30C3F: strcat (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4012A0: makeRacer (racer.c:62) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== Address 0x542009c is 9 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
0=two----o> Thread 3: 
==18972== Invalid read of size 1 
==18972== at 0x401413: run (racer.c:116) 
==18972== by 0x4E416F9: start_thread (pthread_create.c:333) 
==18972== Address 0x5420183 is 0 bytes after a block of size 3 alloc'd 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
        ~X=one----o> Thread 2: 
==18972== Invalid read of         ~X=two----o> 
==18972== at 0x4013C7: run (racer.c:107) 
==18972== HEAP SUMMARY:F9: start_thread (pthread_create.c:333) 
==18972==  in use at exit: 50 bytes in 6 blocksock of size 3 alloc'd 
==18972== total heap usage: 14 allocs, 8 frees, 3,288 bytes allocatedeck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== Thread 1:00F4F: main (pt-cruisers.c:74) 
==18972== 6 bytes in 2 blocks are indirectly lost in loss record 1 of 3 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011DD: makeRacer (racer.c:50) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== 12 bytes in 2 blocks are definitely lost in loss record 2 of 3 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x40124A: makeRacer (racer.c:57) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== 38 (32 direct, 6 indirect) bytes in 2 blocks are definitely lost in loss record 3 of 3 
==18972== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x4011CC: makeRacer (racer.c:49) 
==18972== by 0x400F4F: main (pt-cruisers.c:74) 
==18972== 
==18972== LEAK SUMMARY: 
==18972== definitely lost: 44 bytes in 4 blocks 
==18972== indirectly lost: 6 bytes in 2 blocks 
==18972==  possibly lost: 0 bytes in 0 blocks 
==18972== still reachable: 0 bytes in 0 blocks 
==18972==   suppressed: 0 bytes in 0 blocks 
==18972== 
==18972== For counts of detected and suppressed errors, rerun with: -v 
==18972== ERROR SUMMARY: 797 errors from 15 contexts (suppressed: 0 from 0) 
[email protected]:~/Desktop/Threads$

источник

2016-12-07 ShaolinGOD

Поскольку вы не говорите *, которая * ошибки VALGRIND вы получаете, я бы предположить, что это не нравится отсутствие 'free' звонков ... –

@EugeneSh Я обновляю сообщение с ошибками valgrind. – ShaolinGOD

'size_t sizeOfRacer = sizeof (Racer);' что здесь намерение? – wildplasser

Я не знаю, почему вы отметили линию 49 , но первая ошибка valgrind жалуется на строку 52:

==18972== Invalid write of size 1 
==18972== at 0x4C31644: __strncpy_sse2_unaligned (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==18972== by 0x401208: makeRacer (racer.c:52) 
==18972== by 0x400F4F: main (pt-cruisers.c:74)

Который говорит вам, что (в порядке strncpy) вы пишете в память, которой у вас нет.

Линия 52:

strncpy(nRacer->graphic, rearSide, lengthOfRearSide + 1);

Память для nRacer->graphic была выделена как:

nRacer->graphic = (char *)malloc(lengthOfName);

Таким образом, вы выделены lengthOfName байт, но вы пишете lengthOfRearSide + 1 байт. Это два совершенно разных значения: lengthOfName - 3, но lengthOfRearSide + 1 - 4.

источник

2016-12-07 22:17:02 melpomene

Так что мне нужно назначать либо lengthOfName, либо lengthOfRearSide? – ShaolinGOD

@ShaolinGOD Вы должны выделить достаточно памяти для строк, которые вы собираетесь хранить в переменных. – melpomene

Я просмотрел middleOfCar. Что с этим происходит?

Вы выделяете его здесь:

middleOfCar = (char *)malloc(remain);

затем использовать его здесь:

middleOfCar[x] = '-'; 
    } 
    strcat(middleOfCar, frontSide); 
    strcat(nRacer->graphic, middleOfCar);

но что происходит потом?

Больше ничего .... поэтому вы просачиваете память.

Может быть, вам нужно free его перед выходом из функции

источник

2016-12-07 22:21:01 4386427

должен ли я освободить что-нибудь еще в этой функции? Освобождение middleOfCar устраняло утечку. – ShaolinGOD

@ShaolinGOD - вы должны освободить все, на что не ссылаетесь. – 4386427

Итак, valgrind говорит, что мне нужно освободить nRacer-> графику, но мне нужно вернуть nRacer ... как я могу освободить что-то, что мне нужно, чтобы вернуться? – ShaolinGOD

Как правильно malloc для структуры и определенных переменных?

ответ

Смежные вопросы